This week's situation room photo will likely be marked as one of history's most…
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On May 5, 1961, the 83-foot-tall Mercury-Redstone 3 hurtled Shepard toward space with 78,000 pounds of thrust at sea level, powered by ethyl alcohol and liquid oxygen. Really just a space-worthy version of the US Army's Redstone liquid-fueled ballistic missile, the 66,000-pound lug at its best could travel at almost 7 times the speed of sound (5,143 mph) with a peak acceleration of 108 m/s2.

(Of course, that totally pales in comparison to the rockets of today—each of the pair of Solid Rocket Boosters weighs 1,300,000 pounds at launch and generates 2,800,000 pounds of thrust at sea level.)

At a fundamental level, this thing's a giant bomb. So NASA needed to implement some safety mechanisms. They designed an in-flight abort sensing system so the Mercury capsule (and the astronaut inside) could quickly escape if anything, well, bad started happening. The geniuses at NASA also had to make sure that this thing didn't shut down during the first 30 seconds of flight because it would still be over land. And that would be bad. After lift-off, when the rocket hit a predetermined velocity (calculated by two gyros and an integrating accelerometer), the propulsion system cut off and it would splashdown near the Bahamas.